PURPOSE: To obtain the titled compound useful as an intermediate for synthesizing dye, pigment, agricultural chemical, drug, etc. easily in high yield, by dechlorinating a toluenesulfonic acid derivative with copper or a cuprous compound in sulfuric acid.

CONSTITUTION: A toluenesulfonic acid derivative shown by the formula I (X, Y, and Z are Cl, or H with the proviso that both Y and Z are not H) is reacted with copper or a cuprous compound in 80W5wt%, preferably 25W10wt% sulfuric acid at 80W130°C for 8W30hr, so that chlorine neighboring the sulfone group is eliminated to give the desired compound shown by the formula II. An amount of sulfuric acid is 10W1.5 times as much as the compound shown by the formula I by weight, and an amount of copper of the cuprous compound is 2W6mol based on 1mol compound shown by the formula I .